The following patents have been considered in the preparation of this application: U.S. Pat. Nos. 2,010,546; 2,273,395; 2,657,076; 2,836,436; 3,528,260; 3,788,394; 4,408,467; 4,480,857; and 4,793,150 and 5,048,873.
In a typical automobile air-conditioning system presently in use, refrigerant is conveyed through a fluid transport system connecting the compressor to the condenser and the evaporator, consisting of flexible hoses combined with rigid tubing to accommodate the vibration and movement existing between the vehicle frame, upon which the condenser and evaporator are rigidly affixed, and the vehicle engine upon which the compressor is rigidly affixed.
Refrigerant utilized in automobile air-conditioning systems has historically been R12 freon, which is a chloroflourocarbon (CFC). More recently, R134a, which is a hydroflourocarbon (HFC), has been adopted and is expected to replace R12 as the dominant refrigerant used in such systems. R134a Refrigerant is extremely expensive, much more expensive than R12. However, with progressive taxation recently placed on R12 refrigerants, its cost will similarly rise. Accordingly, it is important that air-conditioning systems used in automotive vehicles be designed to prevent, to the greatest degree possible, any escape of R134a or R12 refrigerant into the atmosphere. The challenge to develop such a system has intensified because flexible hose assemblies presently used to convey refrigerant through the system permit refrigerant loss by effusion through the hose wall and end fitting connection sites.
Additionally, flexible hoses presently used in automotive air-conditioning systems permit variable levels of moisture ingression, which, over time, greatly reduces the efficiency of the system. Flexible hoses are also subject to twisting during installation, which not only causes premature wear, but also places undesirable stresses and potential sources of leakage at the fittings fastening such hoses to system elements. In contrast, rigid lengths of tubing formed of any one of a wide variety of materials are capable of transporting such refrigerants throughout the air-conditioning system without effusion of refrigerant or infusion of undesirable moisture through the conduit walls. For example, the tubing may be formed of metal such as aluminum, steel or a variety of other metals; however, aluminum is preferred from the standpoint of minimizing weight. Additionally, the tubing may be formed of a wide variety of plastics including but not limited to nylon. In order to utilize rigid lengths of tubing for conveying the refrigerant in an air-conditioning system of an automotive vehicle, while providing a system which meets industry standards with respect to minimizing effusion of refrigerant from and infusion of moisture into the system, it is necessary that the rigid lengths of tubing include flexible connectors that permit pivotal, articulating, and/or rotational movement of one tube section length relative to another.
As is well known in the art, refrigerant in the air-conditioning system of a motor vehicle is transported under varying pressures including pressures potentially as high as 500 psi. Accordingly, it is necessary that any connectors for connecting lengths of tubing have adequate means, for sealing therebetween, to prevent or at least minimize the leakage of refrigerant. As may be appreciated, the challenge is to provide an air-conditioning system including a refrigerant transport system having flexible connectors for fastening together the rigid tubing lengths such that there is no appreciable effusion of refrigerant from or infusion of moisture into the system and, perhaps of a more recent consequence, a refrigerant conveyance and containment system that minimizes or eliminates refrigerant leakage to the atmosphere.